The following generally relates to hand-held power tools and, more particularly, to a torsion-adjustable impact wrench.
In the past, an operator generally used a wrench to manually fasten a fastener, such as a bolt or nut, and judged whether the fastener reached a fastened degree by means of hand inspection upon the fastening. At present, a power impact wrench is increasingly used in fastening operations. However, it is difficult to judge whether a fastener is already in a fastened state when a power impact wrench is used in a fastening operation. Currently, the operator generally judges whether the fastener is fastened by his own pre judgment or in a way that the tool operates in a stalled state. However, this may cause damages to a workpiece and may affect the service life of the power tool. Furthermore, because output torsion of the power impact wrench is unadjustable or an adjustment precision is relatively low, it is difficult for the operator to obtain a desired fastening torsion during a fastening operation, e.g., the output torsion may be so small that the fastener cannot be fastened in place or the output torsion may be so great that the fastener is overloaded, thereby causing wear of the fastener or damages to the workpiece and affecting the service life of the tool.